Pebble-mill.



M. F. ABBE.

PEBBLE MILL.

APPLICATION mum HA3. 9. 1909.

Patented Dec.28,1'909.

NITED STATES OFFICE.

MAX 1?. ABBE, or NEW YORK, N. Y.

rEBBLE-numa.

I Spgcificationof Letters Patent. Patented Dec. 28,1909.

Application filed March.9, 1909. Serial No. 482,243.

This invention-relates to a coniform pebble mill more particularlyadapted for wet grinding, and so constructed that the material'to beground is directly fed into that soT portion of the mill which has thegreatest grinding coefficient. y

In the accompanying drawing: F igure 1 is longitudinal section ofmyimproved pebble mill; Fig.2 an end View thereof; Fig.3 a vertical crosssection on line 33, Fig. 1, and Fig. 4 a side view, partly in section,of a modification of the mill.

The shell or barrel 10, forming the grinding chamber of the mill, iscomposedof two frusto-conical sections joined attheir base, sothat theshell tapers from the center toward both ends These ends terminate inhollowtrunnions 11,.turning in bearings 12 of standards 13. Shell 10contains pebbles, balls or similar grinding bodies 14 which areconfinedwithin the grinding chamber.

by grates 15 formed on discharge nozzles 16. hese nozzles. are fittedinto trunnions ll andv are bolted thereto, as at 17.

As described in a companion application filed on even date herewith,pebbles 14 will 'so arrange themselves automatically during theoperation of the mill, that they will pile up at that portion thereofwhichflhas the Furthermore, as the pebbles are usually of differentsizes, the larger pebbles will here gather, while the pebbles willgradually diminish in size toward nozzles 16. Thus, withtheconstructionsh'ow'n -in Fig. 1, the largest pebbles will be heapedlip-at the centerof the'mill to exercise the greatest grinding force,such force gradulally diminishing toward the discharge nozz es.

be ground to that port-ion of the mill which attacks the same mosteffectively, the center of shell 10, 2'. e., that portion thereof whichhas'the greatest diameter is provided with .a peripheral inlet openingcommunicating with a casing '18 that encompasses the grindmg chamber.;.-'This casing mcloses a helical conveyer 19, the convolutes of whichgradexpenditure of power.

Inorder to directly feed the material to ually decrease in radius andare maintained in vertical uxtapos1t1on. Casing-18 encompasses shell 10at its greatest diameter and'is fitted between apair of flanges QOofshell 10, to which it is bolted, as at 21. v

The outer convolute of conveyer 19 is pro- ;vided with a replaceable.scoopor mouthpiece 22 which dips into a trough 23 arranged below casing18 and containing the material to be ground. The inner convolute of theconveyer communicates with the peripheral inletopening of the shellwhich contains a removable grate 24, through which the material to beground is admitted to the grinding chamber, while the escape of pebbles14: is prevented.

When the mill is rotated by a gear wheel 25 and a suitable power-shaft,(not shown), the material to be ground will, by conveyer 19, be carriedto the center of the mill, to be here subjected to the most intensegrinding action, while the, more or less comminuted particles willundergo'a further reduction as they are forced toward discharge nozzles16. In this way the grinding capacity of the mill is fully utilized witha minimum In Fig. 4, the shell 26 of the mill is of frusto-conical form,so that it is widest, not at the center, but at one of its ends. 1 Heretoo the material to be ground is fed to the grinding chamber through ahelical couveyer 27, inclosed within a casing 28 which is fitted to thewidest portion of the shell, so that the grinding capacity of the millis fully utilized.

I claim:

1. A pebble mill comprising a coniform shell having a" peripheral inletopening at the widest portion thereof, a pair of supporting bearings,means for axially rotating the shell, grinding bodies inclosed withinthe shell, a casing encompassing the shell at the'widest portionthereof, a spiral conveyer within the casing and communicating with theinlet opening, and a trough into which said conveyer is, adapted to dip-2. A pebble mill comprising a coniform' shell having-a peripheral inletopening at the widest portion thereof, a pair of trunnions, one of whichis hollow, .means for axially rotating the shell, grinding bodiesinclosed within the shell, a casing encompassing the shell at thewidestortion thereof, a spiral conveyer within tlFe casing and a trou hintowhich said conveyer is adapteral inlet opening.

- y 1 communicating with the inlet opening, and 1 portion andcommunicating with the periph- [0 ed to ip. Signed by me at New Yorkcity, (Man- 3. A pebble mill comprising a coniform hatt-an,) N; thls 8thday of March, 1909.

axially rotatable shell having a peripheral M AX E ABBE. inlet openingat its widest ortion, grinding Witnesses; v means mclos'ed within'theell, and a spiral FRANK BRIESEN,

I conveyer encompassing the shell at its widest E W SCHORR,

